In order to comply with statutory emission limit values, modern motor vehicles have a tank venting device. The main part of the tank venting device is a fuel vapor reservoir which is preferably designed as an activated carbon canister. The fuel vapors contained in the fuel tank are delivered by way of a connecting pipe to the activated carbon canister where they are absorbed by the activated carbon and stored in this manner. The activated carbon canister needs to be regenerated from time to time. To this end, the fuel vapor reservoir is connected by way of a tank venting pipe and a tank venting valve arranged therein to the induction manifold of the internal combustion engine of the motor vehicle. The absorbed fuel vapors are drawn into the intake tract of the internal combustion engine on account of the vacuum prevailing in the induction manifold and then participate in the combustion process together with the fresh air. In this manner, the emission of fuel vapors from the fuel tank into the environment is reliably avoided.
Increasingly stringent legislation stipulates that the operability of the tank venting device must be checked. A method is thus known for example from DE 10 2005 054 880 B3 for checking the integrity of the tank venting device, according to which the tank venting device is initially evacuated by means of the induction manifold vacuum and the integrity of the tank venting device is checked by evaluating the pressure profile therein.
In addition, a method is known from DE 198 36 102 C2 for validating a tank pressure sensor.